Multiple vulnerabilities have been discovered in Pidgin and the
libpurple library:

A participant to the TippingPoint ZDI reported multiple integer
overflows in the msn_slplink_process_msg() function in the MSN protocol
implementation (CVE-2008-2927).

Juan Pablo Lopez Yacubian is credited for reporting a use-after-free
flaw in msn_slplink_process_msg() in the MSN protocol implementation
(CVE-2008-2955).

The included UPnP server does not limit the size of data to be
downloaded for UPnP service discovery, according to a report by Andrew
Hunt and Christian Grothoff (CVE-2008-2957).

Josh Triplett discovered that the NSS plugin for libpurple does not
properly verify SSL certificates (CVE-2008-3532).

Impact

A remote attacker could send specially crafted messages or files using
the MSN protocol which could result in the execution of arbitrary code
or crash Pidgin. NOTE: Successful exploitation might require the
victim's interaction. Furthermore, an attacker could conduct
man-in-the-middle attacks to obtain sensitive information using bad
certificates and cause memory and disk resources to exhaust.